Container closure with liner and methods of making the same

ABSTRACT

A container closure which is thermoformed from a sheet of two different materials which are bonded together, the material forming the inside of the closure being relatively soft to serve as a liner.

United States Patent [191 Keeler et al.

1111 3,866,845 Feb. 18, 1975 CONTAINER CLOSURE WITH LINER AND METHODS OFMAKING THE SAME [75] Inventors: Frederick D. Keeler, Trumbull;

Carleton Ellis, Jr., Southport, both N 21 Appl. No.: 361,636

3,231,529 Kuhn 215/40 3,258,148 6/1966 Unger l 215/40 3,482,725 12/1969Exton 215/43 R 3,527,375 9/1970 Klein v 215/40 X 3,536,224 10/1970 Greenv 215/40 3,612,322 10/1971 Linkletter 215/40 Primary Examiner-Herbert F.Ross Attorney, Agent, or FirmDarby & Darby [52] U.S. C1. 215/341,215/347 ABSTRACT [51] Int. Cl B65d 53/00 5 Field of Search 215/4 D 40 43A7 341 A container closure which 18 thermoformed from a 215/347 sheet oftwo different materials which are bonded together, the material formingthe inside of the closure [56] References Cited being relatively soft toserve as a liner.

UNITED STATES PATENTS 10 Claims 7 Drawin Fi ures 3,176,867 4/1965Reynolds 215/40 g g 12 e2 2 2 22 :2 33.2: a: lo

\/ n i u 5 l x 100 ,1 l l r I I in M PATENTEU FEB 1 8 I975 A ll lOo (a Ml4 IO l6 FIG. 3 f2 36 UNER 35o I 35 '4 W M A TET TFAL MATERTAL l5 f N 520 v l l I l I00 lOb FOR- SANDWICH J, FIG. 5 TREAT LINEAR 38 v 225*MATERIAL T.

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,4 n M THERMOFORMY WU .R :2 24 TREAT w LINEAR MATERIAL CONTAINER CLOSUREWITH LINER AND METHODS OF MAKING THE SAME This invention relates tocontainer closures and more particularly to container closures which arethermoformed from a sheet of two different materials which are bondedtogether with the material on the interior of the closure serving as aliner.

Closures for containers, such as bottles, are often used with some formof liner adjacent the top wall of the closure to place the liner betweenthe closure top wall and the sealing lip. The liner is used to form aseal to prevent leakage of the container contents.

One well known type of liner is a disc of paper, pulp, cork, softplastic (e.g., vinyl) or other similar material which is eitherforce-fit into the closure or secured to its top wall by a suitableadhesive. While such liners perform their intended function, they addexpense to the manufacturing of the closures in the sense that extramaterial is required and also an extra step in the manufacturing processof inserting the liner into the closure is needed. In addition, where anadhesive is used, any excess adhesive can detract from the taste of thecontainer contents.

In another type of structure the closure itself is formed withprojections, or lips, to engage the sealing lip of the container. Ingeneral, closures of this type are either relatively expensive to make,since they require rather complicated molds and molding procedures, orthey have not functioned satisfactorily. One reason for the lattershort-coming is that the closures sealing projections must be made of arelatively soft and deformable material and it has been found difficultto do this while still making the overall closure strong.

In still another type of closure, shown for example in US. Pat. No.3,243,070 to Hoyle, issued Mar. 29, 1966, a metal foil is laminated as aliner to an outer plastic closure and the closure itself is heat-sealedonto a plastic bottle. Similarly, in'U.S. Pat. No. 3,244,306 to Stolk,issued Apr. 5, 1966, a vinyl plastisol liner is attached to a glassclosure.

In the closures of both of the aforesaid patents, and especially theclosure to Stolk, the material of the liner and of the closure itselfare so dissimilar that they cannot be worked together. For example,glass and the plastisol could not readily be molded or thermoformedtogether.

The present invention relates to a closure which is thermoformed from asheet of two materials which are bonded together. One material, whichforms the outer shell of the closure is relatively hard. Materials forthe outer shell are any suitable plastic, such as polystyrene,polyethylene or ABS, which can be thermoformed. The other material,which is to be used as the closure liner, is softer than the outermaterial. In a preferred embodiment of the invention, a thermoplasticrubber incorporating a plastic component is used. The thermoplasticrubber material has several desirable characteristics, such as, forexample, being a relatively soft material which will form an effectiveseal once the closure is fastened to the container. The material is alsocompatible with the plastic forming the closure outer shell.

As another aspect of the invention, a method is described for formingthe closure and for modifying the characteristics of the liner materialin a manner such as to change itsfriction characteristics.

It is therefore an object of the invention to provide a thermoformedclosure made from a sandwich of two different materials which can bethermoformed.

A further object is to provide a thermoformed closure which is made oftwo dissimilar materials which are bonded together, the inner materialserving as a liner for the closure and being relatively soft.

An additional object is to provide a method of making a closure havingan outer plastic shell by thermoforming the closure from a sheet of twodifferent materials which have been bonded together.

Other objects and advantages of the present invention will become moreapparent upon reference to the following specification andannexeddrawings, in which:

FIG. 1 is an elevational view taken in cross-section, of a closure madein accordance with the subject invention;

FIG. 2 is an elevation view taken in cross-section of the material;

FIG. 3 is a flow diagram showing a method of making the closure;

FIG. 4 and 5 are elevational views in cross-section of other closuresmade in accordance with the invention;

FIG. 6 is a view in cross-section of still another embodiment of theinvention; and

FIG. 7 is a perspective view of a sheet of the laminate material formaking the closure of FIG. 6.

Referring to FIG. 1, a closure of the subject invention is shown ashaving the usual generally circular top wall 12 from which depends agenerally cylindrical skirt wall 14 having screw threads 15 formedthereon. The

bottom end of skirt wall 14 terminates in an outwardly.

extending flange 16.

As is also seen in FIG. I, the closure is formed in its entiretythroughout by two different materials. The first material 100, or outerlayer or shell, which is of the shape generally described above, is madeof a suitable plastic material such as polystyrene, polyethylene or ABS.The inner material 10b is made of a softer material which has beenbonded to the outer material 10a. Therefore, when the closure isfastened to the bottle or other article, the portion of the innermaterial 10b bonded to the closure top wall 12 will act as a sealing rimor sealing liner around the bottles sealing lip (not shown). I

A preferred inner material 10b is thermoplastic rubber which can beprocessed in the same manner as the shell, such as by thermoforming. Onesuitable thermoplastic rubber is sold under the trade name KRATON byShell Chemical Company of New York, N.Y. (Series 2000 and 3000). Athermoplastic rubber, such as KRA- TON, is relatively soft. In addition,since it contains block copolymers of both styrene and butadiene, it canbe worked with plastics. A thermoplastic rubber of this type is quitecompatible with a polystyrene type plastic.

One suitable process for making closures according to the subjectinvention is described below and with respect to FIGS. 2 and 3. In FIG.2 the outer plastic material l0a, which normally comes in the form ofsheets of substantially uniform thickness, and the liner material 10b,which also comes in sheets of substantially'uniform thickness are bondedtogether as shown in box 20 of FIG. 3. It should be understood that thetwo materials 10a and 10b can be supplied in rolls so that a continuousbonding process can be utilized. In a preferred embodiment of theinvention, the material 10a for the closure outer shell is polystyrene.Typical thicknessess range from 0.030 inches to 0.040 inches. Asdescribed previously, the preferred inner material is a thermoplasticrubber, such as KRATON. Typical thicknesses for the material b are inthe range from 0.002 inches to 0.005 inches. The total thickness of thetwo materials when bonded together is preferably in the range from about0.032 inches to 0.045 inches.

The bonding together of the two materials 10a and 10b is carried on byany suitable process, for example, by laminating. Since a plasticmaterial 10a is utilized and since the thermoplastic rubber linermaterial 10b also has some of the characteristics of plastic, thematerials 10a and 10b can be heated to a semi-softened form and thenlaminated together by the application of suitable heat and pressure, forexample, by heated rollers.

The two materials also can be bonded together using a suitable adhesiveand heat and/or pressure as required.

Instead of laminating the two materials 10a and 10b together, they canbe coextruded. That is, the raw material for each product, in the formof pellets, chips, liquid, etc., are suitably softened before beingpassed through the extrusion die. The two different materials are fedinto the die adjacent one another. Since the materials are somewhatdifferent, they will not totally mix. However, since they alsopreferably contain the same polymer, there will be a bond produced atthe interface of the two materials.

The sandwich of the two materials formed by laminating, coextrusion orother process is shown in FIG. 2. In general, the sandwich is in sheetform of a predetermined size or is made in rolls. Both types of stockcan be fed to the molding machine.

In the broad context of bonding the two materials 10a and 10b together,it should be understood that this also can be accomplished in thethermoforming equipment. That is, for example, two sheets of material10a and 1017 are merely laid one on top of the other in the formingequipment. As the thermoforming of the closure takes place, the heatcycle, and/or pressure exerted by the assist plugs if used, issufficient to bond the materials together.

Where a material such as thermoplastic rubber material is utilized, ithas been found that such material has a relatively high coefficient offriction. Depending upon a particular application to which the closureis to be put, this characteristic can be either advantageous ordisadvantageous. For example, a high coefficient of friction would meanthat a large torque force would be required to unscrew the closure fromthe bottle. In some cases, such as where the closure is to be used withpharmaceutical and similar products which are to be kept away fromchildren. the large opening force required can be an advantage.

Where the large force needed to screw the cap onto or unscrew it fromthe closure is not desired, the liner material 10b can be treated priorto thermoforming to reduce the coefficient of friction. One way ofaccomplishing this is to treat the material with a suitable antifrictionagent. In the case of thermoplastic rubber materials, such as KRATON,suitable agents are silicone, wax, oil, fluocarbon compounds, etc. Theseagents can be applied to the liner material 10b while it is still insheet form, when it is in the mold being thermoformed, or between themolding and trimming steps. The treatment step is represented in block22 of FIG. 2. The anti-friction agent makes the material 10b somewhatmore slippery" so that it can be torqued onto and off of the closurewith a smaller amount of force. It should be understood that thetreatment step 22' is optional and may be dispensed with entirely.

Liner materials 10b of the type described above can be thermoformed in amanner similar to other plastic materials such as polyethylene and ABS.Thus, the sheet laminate of the two materials shown in FIG. 3 can beutilized in conjunction with any conventional thermoforming machine andprocess to produce a closure of the type shown in FIG. 1. For example,the thermoforming machine and process represented by block 24, caninclude a female mold on which the sheet material has been layed after.After being softened by any conventional apparatus such as heaters,lamps, etc., the sheet material is then sucked or forced into the femalecavities. A plug assist may be utilized if desired. In anotherconventional thermoforming technique a plurality of male molds areutilized and the plastic material is draped over the male molds,softened and then molded to produce the finished closure. The lattertechnique is not as desirable since the higher coefficient of frictionof the material 10b makes itmore difficult to remove from the molds.

The particular thermoforming process and equip ment utilized to producethe closure of FIG. 1 or of the other embodiments of the invention isnot part of the subject invention except in the sense that the closuresare produced from the sandwich of two different materials. Typicalapparatus and methods for thermoforming the closures of the subjectinvention are described in the issued patent to Childs and Ostrowski,U.S. Pat No. 3,606,063, issued Sept. 20, 1971 which is assigned to theassignee of the subject application.

During the thermoforming of the closure, the sheet material is deformed,or thinned out, in the areas where bends and other curves are made. Thisis, for example, at the screw threads, the place where the skirt walljoins the top wall. Thus, the closures outer shell material 10a is ofsubstantially uniform thickness throughout except in the areas where thedeformation occurs. The same is true for the inner liner material 10b.

The closures which have been thermoformed from the sheet material areremoved from the mold by any conventional stripping technique. Thesheets are then trimmed in the area of the flange to produce theindividual closures. Trimming is accomplished by any conventionalapparatus.

In a typical manufacturing arrangement, the closures come out of thethermoforming apparatus in sheet form, with a number of closures on asheet, or as a continuous roll of the sheets. The trimming station canbe separated in type and/or space from the thermoforming station topermit another process step to be carried out. For example, one or moreidler" rollers can be located between the two stations by which thesheets are fed. In any event, the closures are still in a form wherein anumber of them can be processed at the same time.

It is possible as described above, to add the antifriction agent to theclosures between the thermoforming and trimming stations. Instead ofadding such an agent, the liner material can be otherwise processed. Forexample, it has been found that subjecting the liner material 10b toultraviolet light or to ozone will reduce its coefficient of friction.It is believed that either of these two processes oxidize the moleculesof the thermoplastic rubber. The alternate process is shown by thedotted line block 22a of FIG. 3.

The liner material b can be diluted by the addition of the shellmaterial 10a in the case where the two have the same copolymers. Thishas several advantages. First, the dilution can be used to control tosome extent the coefficient of friction of the material. Secondly, thedilution lowers the overall cost of the liner material. Thirdly, theexcess scrap (liner plus shell) material produced during trimming can berecycled with a higher concentration of the liner material to produceadditional liner material. The latter is possible only where the linermaterial and shell material are compatible, that is, are of the samecopolymer.

After the closures are trimmed they are ready to be placed onto thecontainer which they are to seal. This is done by any conventionalcapping equipment. Usually, high speed automatic equipment is utilized.The closures of the subject invention can be used with this equipmentwithout modifying it.

In the closure of FIG. 1, as well asthe other embodiments disclosedherein, the additional manufacturing.

step of inserting a liner into the closure is completely eliminated.Also eliminated are the other attendant problems of liners which fallout of the closures, liners which are improperly placed and do noteffect a good seal, adhesive spread onto the liner to possiblycontaminate the products inside the container, and other similarproblems.

As an additional advantage, by controlling the coefficient of frictionof the liner material 10b in the area of the screw threads 15 of theclosure, the amount of torque needed to open the closure can becontrolled.

While the closure made by the laminated material in accordance with theinvention has been shown as being of relatively conventional shape witha flat top wall, it should be understood that other shapes can beutilized. Reference is made to FIG. 4 in which the closure correspondssubstantially to that shown in US. Pat. No. 3,482,725 to Norman T.Exton, issued Dec. 9, 1969 which is assigned to the assignee of thesubject application. In the closure of FIG. 4 the top wall 12 has beenmodified to produce a generally U-shaped downwardly extending sealingring 35 leaving a space 36 in the top wall. The laminate of the twomaterials 10a and 10b is again used.

In the closure of FIG. 4, the sealing ring 35 is located with respect tothe inner surface of the closure skirt wall 14 and the inner edge of thecontainer sealing lip (not shown) so that the outer surface 35a of ring35 engages the inner edge of the sealing lip. As the closure is torqueddown onto the container, thesealing ring 35 deforms down and over thecontainer sealing lip. There is a deformation of the ring 35 over thesealing lip and a closing up of the space 36. The advantages of theintegral liner produced by thermoforming are obtained. The otherclosures shown in the Exton patent also can be thermoformed from thelaminate of the two different materials.

FIG. 5 shows another embodiment of closure which corresponds in largemeasure to.that shown in US. Pat. No. 3,606,063 to E. Childs et al.granted Sept. 20, 1971 and assigned to the assignee of the subjectapplication. Again, the laminate of the two materials 10a and 10b isutilized with thermoforming process. The closure of FIGS has an indentedring 38 on the skirt wall ad ja Mr cent the top wall 12. The ring, whoseinternal diameter is somewhat smaller than the outer diameter of thecorresponding top portion of the bottle which the ring en gages,prevents doming of the closures top wall and also provides a tight seal.1

The features of the two closures of FIGS. 4 and 5 ca be combined. Forexample, the closure of FIG. 5 can have its top wall 12 modified to havethe sealing ring 35.

FIG. 6 shows still another embodiment of closure in which the linermaterial 10b'is present only in the top wall 12. If desired, and asshown in FIG. 6, the liner material also can extend downwardly slightlyin the junction area with the skirt wall onto the skirt wall, as shownin the area 41. r

The closure of FIG. 6 is also made by thermoforming,

in the manner previously described. Here, however, the

sheet material supplied to a multiple mold thermoforming equipment takesthe shape shown in FIG. 7 .where a plurality of discs 10b are laid' downon the sheet of closure material 10a. The discs 10b of the linermaterial are of a shape corresponding to the top wall 12 of the closure.If the extending area 41 is to be provided, the discs are made slightlyoversized. The discs 10b are laid down on the sheet of closure materialin a matrix pattern corresponding to the mold configuration of thethermoforming machine. That is, each of the discs 10b will register withthe portion of the corresponding plug or cavity which will form the topwall of the closure. In this embodiment of the invention, individualsheets of the laminate, base material 100 plus discs 10b, are preferablysupplied to the thermoforming machine instead of using material from aroll. This simplifies the registration problem at the machine.

The discs 10b are bonded to the base material 10a in any of the waysdescribed previously. In addition, for example, the discs l0b' can bedie cut and laid down on an adhesive backed sheet which is then laidover the base sheet 10a. After the bonding takes place, the adhesivebacked sheet is removed. As an alternative to this, a multiple cavitytool is formed corresponding to the pattern of the discs to be laid out.The-discs are fed directly from the cavities of the tool onto the basesheet 10a. If desired, the individual discs can have a small quantity ofadhesive thereon to hold them in place once they are laid down on thebase sheet 10a.

The closure of FIG. 6 has advantages in that there is a saving of linermaterial 10b since it is not applied to the skirt wall. Also, the forceneeded to torque the closure onto or off of the container is reducedsince there is no liner material in the area of the screw threads.

while the closures of the present invention have been shown withscrew-threads, it should be understood that other conventional fasteningarrangements can be utilized, for example, interrupted threads, bayonetthreads, etc. It is also possible to form the closures without anythreads and to seal them to the container by other means.

What is claimed is:

l. A thermoformed container closure comprising:

an outer shell of plastic material ofsubstantially uniform thicknessthroughout except in the areas where deformed and having a top 'wall anda skirt wall depending therefrom,

and a thermoformed liner of a material different from and softer thansaid shell material and of substantially uniform thicknessthroughoutexcept in the areas where deformed bonded to the interior ofsaid outer shell throughout the entire inner surface area of said shell.

2. A container closure as in claim 1 wherein said liner material is ofthermoplastic rubber.

3. A container closure as in claim 1 wherein the skirt wall includesmeans for fastening the closure to the container, said liner materialcovering at least a portion of said fastening means.

4. A container closure as in claim 3 wherein said fastening meanscomprises threads.

5. A container closure as in claim 1 further compris ing ananti-friction agent on at least a portion of said liner material.

6. A container closure as in claim l'wherein said liner materialcomprises material treated prior to use on the closure to reduce itscoefficient of friction from that in its normal state.

7. A container closure as in claim 6 wherein the liner 8 materialcomprises material subjected to ultraviolet light to reduce itscoefficient of friction.

8. A container closure as in claim 6 wherein the liner materialcomprises material subjected to ozone gas to reduce its coefficient offriction.

9. A thermoformed container closure comprising:

an outer shell of sheet plastic material of substantially uniformthickness throughout except in the areas where deformed and having a topwall and a skirt wall depending therefrom,

and a thermoformed liner of a material different from and softer thansaid shell material andof substantially uniform thickness throughoutexcept in the areas where deformed bonded to the interior of said outershell at least in the area of said top wall prior to the thermoformingof said closure.

10. A container closure as in claim 9 wherein said inner material is ofthermoplastic rubber.

1. A thermoformed container closure comprising: an outer shell ofplastic material of substantially uniform thickness throughout except inthe areas where deformed and having a top wall and a skirt walldepending therefrom, and a thermoformed liner of a material differentfrom and softer than said shell material and of substantially uniformthickness throughout except in the areas where deformed bonded to theinterior of said outer shell throughout the entire inner surface area ofsaid shell.
 2. A container closure as in claim 1 wherein said linermaterial is of thermoplastic rubber.
 3. A container closure as in claim1 wherein the skirt wall includes means for fastening the closure to thecontainer, said liner material covering at least a portion of saidfastening means.
 4. A container closure as in claim 3 wherein saidfastening means comprises threads.
 5. A container closure as in claim 1further comprising an anti-friction agent on at least a portion of saidliner material.
 6. A container closure as in claim 1 wherein said linermaterial comprises material treated prior to use on the closure toreduce its coefficient of friction from that in its normal state.
 7. Acontainer closure as in claim 6 wherein the liner material comprisesmaterial subjected to ultraviolet light to reduce its coefficient offriction.
 8. A container closure as in claim 6 wherein the linermaterial comprises material subjected to ozone gas to reduce itscoefficient of friction.
 9. A thermoformed container closure comprising:an outer shell of sheet plastic material of substantially uniformthickness throughout except in the areas where deformed and having a topwall and a skirt wall depending therefrom, and a thermoformed liner of amaterial different from and softer than said shell material and ofsubstantially uniform thickness throughout except in the areas wheredeformed bonded to the interior of said outer shell at least in the areaof said top wall prior to the thermoforming of said closure.
 10. Acontainer closure as in claim 9 wherein said inner material is ofthermoplastic rubber.